Figure 1.

Compartment model of TSP1 and VEGF. The model is comprised of a single compartment representing a solid breast tumor and involves 18 molecule types. The soluble species TSP1, VEGF₁₂₁, VEGF₁₆₅, proMMP9, and MMP3 are secreted by endothelial cells. Tumor cells secrete VEGF₁₂₁ and VEGF₁₆₅. Other soluble species can be formed, including cleaved TSP1, active MMP9, and VEGF₁₁₄. All soluble species are subject to degradation. TSP1 receptors (CD36, CD47, β1, and LRP1) and VEGF receptors (R1, R2) and co-receptors (N1, N2) are localized on endothelial and tumor cells. Glycosaminoglycan (GAG) chains are present in the interstitial space, representing the extracellular matrix and endothelial and parenchymal cell basement membranes.